1. Field of the Invention
The present invention relates to an air bag apparatus which expands in an instant for protecting a passenger of an automobile at the time of collision of the automobile, especially at the time of a side-on crash in which other automobile crashes into a side of the automobile.
2. Description of the Related Art
A conventional air bag apparatus will be described hereinafter.
In a gas bag-type side collision protecting apparatus, a bag body is normally folded and accommodated in a housing in a seat back. An inflator is arranged at a position facing a gas inlet port of the bag body, and is ignited by a signal of a shock detecting sensor at the time of the side-on crash of the automobile to generate gas. Gas is introduced through the gas inlet port into the bag body to expand the bag body. The bag body expands forward from the seat back, and is developed in a space between the passenger and a side wall in the passenger's room. A shock generated when the passenger secondary collides against a side wall of the passenger's room is absorbed by the bag body (see Japanese Patent Application Laid-open No.9-123864, for example).
The bag body is divided into a portion supporting the head of the passenger and a portion supporting the chest of the passenger, or is integrally formed, so that gas discharged by the inflator is charged into the bag body in a short time.
It is experimentally confirmed that the behavior of the secondary collision of the passenger at the time of the side-on crash is such that the chest of the passenger strongly collides against the side wall in the passenger room such as to lash around waist, and subsequently, the head of the passenger strongly collides against the side wall in the passenger room.
However, with the structure of such an air bag apparatus, since gas discharged by the inflator is at a high temperature, it is necessary that the bag body into which the high temperature gas is charged can withstand such a high temperature, and which is one cause for increasing the costs , and the improvement thereof is required.
Further, if the bag body expands on at least a wearing track of the shoulder belt among the wearing track of the seat belt comprising the shoulder belt and lap belt for binding the chest and waist of the passenger sitting on the seat back, the belt is pushed, and there is an undesirable possibility that the webbing of the belt may be separated from the passenger. Further, the expansion of the bag body may be hindered by the belt, an improvement of this point is also required.
Furthermore, it is necessary to provide the bag body with means for guiding a flow of gas into the head supporting portion and the chest supporting portion of the bag body, and which is one cause for increasing the costs, and the improvement thereof is required.